/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;

/**
 * Basic implementation of the {@link ListMultimap} interface. It's a wrapper around
 * {@link AbstractMapBasedMultimap} that converts the returned collections into {@code Lists}. The
 * {@link #createCollection} method must return a {@code
 * List}.
 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
abstract class AbstractListMultimap<K, V> extends AbstractMapBasedMultimap<K, V> implements ListMultimap<K, V> {
    /**
     * Creates a new multimap that uses the provided map.
     *
     * @param map place to store the mapping from each key to its corresponding values
     */
    protected AbstractListMultimap(Map<K, Collection<V>> map) {
        super(map);
    }

    @Override
    abstract List<V> createCollection();

    @Override
    List<V> createUnmodifiableEmptyCollection() {
        return ImmutableList.of();
    }

    // Following Javadoc copied from ListMultimap.

    /**
     * {@inheritDoc}
     *
     * <p>
     * Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link Collection} specified in the
     * {@link Multimap} interface.
     */
    @Override
    public List<V> get(@Nullable K key) {
        return (List<V>) super.get(key);
    }

    /**
     * {@inheritDoc}
     *
     * <p>
     * Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link Collection} specified in the
     * {@link Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    public List<V> removeAll(@Nullable Object key) {
        return (List<V>) super.removeAll(key);
    }

    /**
     * {@inheritDoc}
     *
     * <p>
     * Because the values for a given key may have duplicates and follow the insertion ordering,
     * this method returns a {@link List}, instead of the {@link Collection} specified in the
     * {@link Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
        return (List<V>) super.replaceValues(key, values);
    }

    /**
     * Stores a key-value pair in the multimap.
     *
     * @param key key to store in the multimap
     * @param value value to store in the multimap
     * @return {@code true} always
     */
    @CanIgnoreReturnValue
    @Override
    public boolean put(@Nullable K key, @Nullable V value) {
        return super.put(key, value);
    }

    /**
     * {@inheritDoc}
     *
     * <p>
     * Though the method signature doesn't say so explicitly, the returned map has {@link List}
     * values.
     */
    @Override
    public Map<K, Collection<V>> asMap() {
        return super.asMap();
    }

    /**
     * Compares the specified object to this multimap for equality.
     *
     * <p>
     * Two {@code ListMultimap} instances are equal if, for each key, they contain the same values
     * in the same order. If the value orderings disagree, the multimaps will not be considered
     * equal.
     */
    @Override
    public boolean equals(@Nullable Object object) {
        return super.equals(object);
    }

    private static final long serialVersionUID = 6588350623831699109L;
}
